Wireless power feeder and wireless power transmission system

摘要

Power is transmitted from a feeding coil L2 to a receiving coil L3 by magnetic resonance. A VCO 202 alternately turns ON/OFF switching transistors Q1 and Q2 to feed AC current to the feeding coil L2, whereby the AC power is fed from the feeding coil L2 to the receiving coil L3. An AC magnetic field generated by AC current IS flowing in the feeding coil L2 causes inductive current ISS to flow in a detection coil LSS. A phase detection circuit 150 compares the phase of AC voltage generated by the VCO 202 and phase of the inductive current ISS to detect the phase difference between voltage and current phases and generates phase difference indicating voltage indicating the magnitude of the phase difference. The reset circuit 102 forcibly reduces the phase difference indicating voltage when the phase difference indicating voltage exceeds a predetermined threshold.

主权项

1. A wireless power feeder that wirelessly feeds power from a feeding coil to a receiving coil using a magnetic field resonance phenomenon between the feeding coil and the receiving coil, the feeder comprising:
a power transmission control circuit; the feeding coil; an exciting coil that is magnetically coupled to the feeding coil and feeds AC power fed from the power transmission control circuit to the feeding coil; a phase detection circuit that detects a phase difference between a voltage phase and a current phase of the AC power and generates a phase difference indicating voltage in accordance with a magnitude of the phase difference; and a reset circuit that is connected to a voltage line to which the phase difference indicating voltage is fed so as to reduce the phase difference indicating voltage, wherein the transmission power control circuit includes first and second current paths and makes first and second switches connected in series respectively to the first and second current paths alternately conductive to feed the AC power to the exciting coil, the phase difference indicating voltage output from the phase detection circuit is input to the power transmission control circuit, the power transmission control circuit adjusts the drive frequency so as to reduce the phase difference according to the phase difference indicating voltage, and the reset circuit reduces the phase difference indicating voltage when the phase difference indicating voltage exceeds a predetermined threshold.